Day 1 — Ancient Rome: Colosseum, Forum & Palatine Hill
Start early. Book the "Full Experience" ticket online in advance — it covers the Colosseum, Roman Forum, and Palatine Hill on one entry and lets you skip the worst of the queue. Arrive at 8:30am when the gates open; by 10am the arena floor is shoulder to shoulder with tour groups.
Inside the Colosseum, the underground chambers (hypogeum) where gladiators and animals waited before combat are the most striking part if your ticket includes access — book that add-on separately if you can. After the arena, walk down into the Roman Forum, the political and religious centre of the ancient city for over a thousand years. The Via Sacra, the Temple of Saturn, and the House of the Vestal Virgins are the highlights; give yourself at least ninety minutes.
Palatine Hill rises above the Forum and was where Rome's emperors actually lived — the ruins of the Domus Augustana are extensive and the views back over the Circus Maximus are worth the climb. Budget half a day for all three sites combined, more if you're not rushing.
Lunch in Monti, Rome's oldest and now trendiest neighbourhood, a short walk from the Colosseum. Afternoon: wander Monti's vintage shops and wine bars, then head to the Aventine Keyhole for the St. Peter's dome framed through a hedge tunnel — one of Rome's best free surprises. Evening: dinner in Testaccio, the city's real food neighbourhood, away from the tourist menus of the centre.
Day 2 — Vatican City: Museums, Sistine Chapel & St. Peter's
The Vatican deserves a full day. Book Vatican Museums tickets online for the earliest slot you can get (8am or 8:30am) — without a reservation the queue can run past three hours. The museums are enormous; don't try to see everything. Head toward the Raphael Rooms and the Sistine Chapel first while the crowds are thinner, then work backwards through the quieter galleries — the Gallery of Maps and the Pinacoteca are frequently overlooked and worth the detour.
The Sistine Chapel itself needs no introduction — Michelangelo's ceiling and the Last Judgement on the altar wall. No photography is allowed and guards enforce a no-talking rule; go slow and look up for as long as they'll let you.
From the museums, follow the connecting corridor (or exit and re-enter via St. Peter's Square) to St. Peter's Basilica — free entry, but expect a security line. The basilica's scale is difficult to process from photographs; Michelangelo's Pietà sits just inside the entrance. Climb the dome (551 steps, or take the lift partway) for the best panoramic view in Rome, looking straight down Via della Conciliazione and across the entire city.
Lunch or dinner in Prati, the Vatican-adjacent neighbourhood with wider streets and noticeably better value than anything immediately around St. Peter's Square. For pizza al taglio, Bonci Pizzarium near the Vatican is considered among the best in the world — worth the small detour.
Day 3 — Baroque Rome, Trastevere & the Food Scene
Morning: the Pantheon, free to enter and best experienced early before the tour groups arrive. The dome remains the largest unreinforced concrete dome in the world nearly 1,900 years after it was built. From there, walk to Piazza Navona for Bernini's Fountain of the Four Rivers and the general theatre of Baroque Rome, then to the Trevi Fountain — go early or you'll be fighting crowds all day.
Late morning: Campo de' Fiori for its market stalls, then wander the lanes of the Centro Storico between the two piazzas — this is Rome at its most photogenic, though also its most expensive for a sit-down meal.
Afternoon: cross the Tiber to Trastevere. Walk without a plan — this is the point. Ivy-covered buildings, small workshops, and Piazza di Santa Maria in Trastevere with its 12th-century mosaic-fronted basilica. If you have energy, the Gianicolo hill above the neighbourhood has a sweeping view over the whole city, best at sunset.
Evening: dinner properly. Da Enzo or Roscioli for carbonara or cacio e pepe — book ahead or expect a wait. Finish with an aperitivo at Freni e Frizioni, a converted mechanic's garage in Trastevere that does the pre-dinner ritual with a generous buffet of snacks. This is the neighbourhood to end a Rome trip in — noisy, warm, and unmistakably Roman.